The present invention relates to a solenoid valve used suitably for pressure control of various fluids or the like.
Conventionally, a solenoid valve of this type is shown in, for example, FIG. 7. FIG. 7 is a schematic, cross sectional view showing a construction of a solenoid valve of the conventional art.
A solenoid valve 200 comprises a solenoid section 200A and a valve section 200B.
Here, the valve section 200B comprises a spool valve constructed such that since an opening area of the valve is varied according to a stroke of a spool, a solenoid controls a stroke amount of the spool to be able to control an amount of inflow and an amount of outflow.
The solenoid section 200A generally comprises a coil 203, a plunger 201 adapted to be magnetically attracted to a center post 202 upon energization of the coil 203, and a rod 204 connected to the plunger 201 to transmit driving of the plunger 201 to the valve section 200B (concretely, the spool), a casing member 208, into which various solenoid constituents are incorporated, and a connector 211 for feeding electricity to the coil 203.
Also, a first bearing 205 and a second bearing 210 for increasing a coaxiality of the plunger 201 and the rod 204, which reciprocate, are provided, and the rod 204 fitted into the plunger 201 is supported by the bearings 205, 210, one of the bearings 205 being supported by a sleeve 206. The other of the bearings 210 is supported by the center post 202. Also, provided are an upper plate 207, which forms a magnetic path, and the like.
Here, the plunger 201 is configured to be positioned in a direction away from the center post 202 in a normal state, that is, a state, in which electricity is not fed to the coil 203.
In addition, generally, a biasing member such as springs, or the like, biases the plunger 201 in a direction away from the center post 202. In an example shown, a spring for biasing the spool toward the solenoid section 200A is provided whereby the plunger is spaced away from the center post 202 through the spool.
So, electricity is fed to the coil 203 to thereby form a magnetic path, so that the plunger 201 is magnetically attracted to the center post 202.
Accordingly, magnetic forces can be controlled according to a magnitude of current fed to the coil 203, so that an amount of movement of the plunger 201 is controlled to enable controlling an amount of stroke of the spool, thus enabling controlling a flow rate of a fluid, pressure control, such as hydraulic control, of various fluids, or the like.
Here, the solenoid valve 200 of the conventional art is assembled by suitably incorporating various solenoid constituents, which include the plunger 201 and the center post 202, in a hollow portion of the substantially cylindrical-shaped casing member 208 from both end sides of the casing member 208 according to shapes, or the like, of the respective member, thereafter caulking a caulked portion 208a, which is provided on one end side of the casing member 208, on an end of the upper plate 207 and further caulking a caulked portion 208b, which is provided on the other end side, on an end of the valve section 200B (however, the caulked portion 208a is not always caulked first in a caulking order).
Hereupon, in the case where the connector 211 is of a type to be arranged in a portion of a rear end of a solenoid valve body in a circumferential direction as in the solenoid valve 200 of the conventional art shown in FIG. 7, there is involved a disadvantage that interchangeability is bad since the positional relationship between the connector and a bracket 212 for mounting the solenoid valve body in a predetermined mount position must be modified according to a mount location.
Here, in order to improve interchangeability, there is known a type, in which a connector 311 is disposed on a rear end of a body of a solenoid valve 300 to project outside from one end of a casing member 308 as shown in FIG. 9.
In this case, since the connector 311 is structured to project outside from one end of the casing member 308 to be disposed on an axis, there is no need of taking account of the positional relationship between the connector and a bracket, which makes interchangeability excellent.
In the case of this type, assembly is performed by forming a step portion 311a on the connector 311, which is molded by insert molding of a connector terminal, and caulking a caulked portion 311a, which is provided on one end of the casing member 308, on the step portion 311a. 
Here, since that portion, in which a metallic upper plate 312 is formed integral with a resin material, involves a relative difference in coefficient of linear expansion between the resin and the metal, a gap is liable to be produced due to repeated thermal expansion and contraction (temperature change).
Also, that portion, in which the resin is fixed by caulking of the casing, is liable to generate a gap because the caulked portion is partially strained.
Therefore, a seal ring O is provided in order to prevent water from entering into a coil from outside through the gap to generate such malfunction as short circuit, or the like.
As described above, with the solenoid valve of the conventional art, various solenoid constituents must be assembled into the casing member 208 from both sides thereof, and so the casing member 208 must be suitably reversed in the assembling process, which causes an increase in manhour for assembly and complexity in the assembling work.
Also, since various solenoid constituents must be assembled from the both sides, a caulking processing is necessary in two locations on the both sides in order to provide fixing of the various constituents.
In addition, in the case where a seal ring is to be assembled to an inner periphery of the casing member, when the seal ring remains long in a state, in which it slides on and contacts with an inner periphery of the casing member, at the time of assembly, there is a fear that abrasion of the seal ring and worsening of a mount state, such as distortion of the seal ring, are caused to degrade the sealing performance, and so there is a demand for prevention of such matter.
Also, accuracy in inner diameter and accuracy in surface condition are demanded for those portions, against which the seal ring abuts, and an outer periphery of the upper plate consituting a magnetic flux feeding portion abuts, in an inner peripheral portion of the casing.
Also, the above conventional art involves a problem that bearings cause shaft deviation to lead to lowering of accuracy in coaxiality. Here, coaxiality means positional accuracies of a plunger and a rod, which move reciprocatingly in an axial direction. That is, the closer to a central axis of the whole solenoid valve axes of a plunger and a rod making reciprocation, the higher these accuracies. Such coaxiality is determined by positional accuracies among respective members, and in particular, when bearings cause shaft deviation, accuracy in coaxiality is lowered.
In this manner, when bearings cause shaft deviation and accuracy in coaxiality is lowered, a plunger and a rod are increased in sliding resistance, which is responsible for degradation in function, such as generation of hysteresis, or the like.
As the reason for causing shaft deviation, it is first cited that a caulked portion is near a portion, by which an outer periphery of the plate is held.
That is, the casing is liable to be susceptible of deformation in the vicinity of the caulked portion, and that member, on which load of caulking is applied, becomes liable to be susceptible of positional deviation.
Meanwhile, the plate is generally a member that affects positional accuracies of various constituents constituting a solenoid much. This is because a sleeve and the like are joined integrally to the plate and the plate positions bearings through other several members. Also, the plate is positioned with its outer periphery abutting against an inner periphery of the casing.
Accordingly, when the plate is disposed in the vicinity of that portion, which is subjected to caulking, positional deviation is increased due to deformation of the casing and load of caulking with the result that there is caused shaft deviation.
Also, as the reason for causing shaft deviation, it is second cited that the configuration does not define a position, in which a portion being caulked is bent.
More specifically, while caulking is conventionally performed by caulking an entire circumference of an end of a casing, or providing a projection for caulking to caulk the same, a position, in which a portion being caulked is bent, depends only on a jig (metallic die for caulking) for carrying out caulking.
Accordingly, since a metallic die for caulking generally has a portion, of which inner surface is in the form of a curved surface, pressing against a caulking projection, or the like, to perform caulking so that a portion being caulked is smoothly bent, the portion being caulked is liable to bulge at its root.
Accordingly, when the plate is present on such bulged portion, a gap is generated between an outer periphery of the plate and an inner periphery of the casing, and so the plate becomes liable to make deviation with the result that shaft deviation is increased.
These points will be concretely explained taking as an example the solenoid valve shown in FIG. 7.
The solenoid valve shown in FIG. 7 is configured such that the caulked portion 208a is caulked on the end of the upper plate 207 as described above. Accordingly, a root of the caulked portion 208a is liable to be deformed in a bulging manner, and the upper plate 207 is directly acted by load of caulking to be liable to cause positional deviation.
Meanwhile, the sleeve 206 is joined integrally to the upper plate 207 and supports the bearing 205. Accordingly, when the upper plate 207 causes shaft deviation, the bearing 205 also causes shaft deviation, so that accuracy in coaxiality is lowered.
Also, there is also caused a further problem that spring back is generated at the caulked portion and therefore no adequate fixing force for caulking is obtained.
Such matter will be explained with reference to FIG. 8 showing an enlarged view of the caulked portion 208b in FIG. 7.
Generally, caulking is performed by bending a tip end of a caulked portion up to a position, in which it abuts against a wall surface of a mating-member. That is, in the example shown, a tip end of the caulked portion 208b is bent up to a position, in which it abuts against an outer wall surface of the valve section (portion shown by a dotted line in FIG. 9).
Since the casing is metallic, however, the caulked portion 208b is deformed to be returned a little to an original by its elastic righting force, that is, spring back is generated.
In this manner, since the tip end of the caulked portion 208b causes spring back in a direction of an arrow B in FIG. 8 to be deformed up to a position shown by solid lines after caulking is performed, there is in some cases generated a gap and not obtained an adequate fixing force for caulking.
Accordingly, in the case where an adequate fixing force for caulking is not obtained, various constituents are inadequately positioned, which is responsible for degradation in function.
Further, with the constitution of the solenoid valve of the conventional art shown in FIG. 9, load of caulking is applied on the resin material among the various solenoid constituents, deformation is liable to be generated, which is also responsible for worsening of positional accuracies between the respective members.
Accordingly, with the solenoid valve 300 shown in FIG. 9, it is necessary to take adequate account of a burden on the resin material, on which load of caulking is applied, and so a wall thickness L0 from the groove, in which the seal member O is mounted, to the end surface must be made sufficiently large.
The present invention has been thought of in order to solve the problems of the conventional art, and has its object to provide a solenoid valve, in which improvement in assembling work and quality is achieved.
To attain the object, the invention provides a solenoid valve including a substantially cylindrical-shaped casing member having on one end side thereof a bent portion, which is bent inside, a connector member adapted to be inserted into a hollow interior of the casing member from other end side thereof, and having a stepped portion positioned on the bent portion, the connector member having a connector portion projecting outside from the one end side of the casing member, various solenoid constituents adapted to be sequentially inserted into the hollow interior of the casing member from other end side thereof after the connector member has been inserted, and a valve adapted to be mounted after the various solenoid constituents have been inserted, the solenoid valve being characterized by having projections for caulking, by which the valve and the various solenoid constituents are mounted in a state, in which the valve is mounted on the other end of the casing member.
Accordingly, it suffices to assemble all the various solenoid constituents from the other end of the casing member, the process of reversing the casing member in the assembling processing is made unnecessary, and it suffices to perform caulking only in one location. Also, since the connector section is constructed to project outside from one end side of the casing member, the positional relationship in a direction of rotation involves freedom as compared with that arrangement, in which a connector is provided on an outer peripheral surface of a casing member, which makes interchangeability excellent. Further, since caulking is performed only on the other end of the casing member, a burden of load on the connector member disposed on one end side is small at the time of caulking. Also, since caulking is performed by the projections for caulking, deformation near a portion being caulked is small as compared with the case where caulking is performed over an entire periphery of the end.
The valve is preferably provided with a first corner for prescribing a position, in which the projections for caulking begin bending at the time of caulking, and a second corner adapted to be pressed by those inner peripheral surfaces of the projections for caulking, which are bent by the first corner.
Thereby, the first corner is provided on the valve to prescribe a position, in which the projections for caulking are bent, and the second corner is provided to be pressed by the projections for caulking, so that an adequate fixing force for caulking is obtained. Also, even when spring back causes tip ends of the projections for caulking to be separated from the wall surface of the valve, the second corner remains pressed, so that an adequate fixing force for caulking can be maintained.
The projection for caulking is preferably provided with a groove, which extends near the first corner from a tip end of the projection.
Thereby, the projections for caulking are smoothly bent near the first corner.
It is preferable that a bracket plate, in which a bracket for mounting a solenoid valve body to a different element, and a plate provided on a side of the valve for forming a magnetic path between the casing and the solenoid constituents are formed integrally, is provided, one end of the valve portion abuts against one surface of the bracket plate and a portion of an end edge of the casing on the other end side thereof abuts against the other surface of the bracket plate, and the projections for caulking effect assembling of the various solenoid constituents and the valve in a state, in which an inner peripheral surface of the casing extends along and abuts against at least a part of an outer peripheral, curved surface of the bracket plate, or in a state, in which the inner peripheral surface of the casing extends along and abuts against at least a part of an outer peripheral surface of the valve, or in a state, in which the inner peripheral surface of the casing extends along and abuts against both of at least a part of the outer peripheral, curved surface of the bracket plate and at least a part of the outer peripheral surface of the valve.
Here, xe2x80x9cformed integrallyxe2x80x9d means a configuration, in which a plurality of parts (in this case, the bracket and the plate) are joined to a member by means of welding, caulking, concave and convex fitting, or the like, or a configuration, in which a member (for example, a sheet of steel) is formed into a part by means of press, or the like.
Accordingly, since inner peripheral surfaces of the projections for caulking are caulked while abutting along with at least a part of the outer peripheral, curved surface of at least one of the bracket plate and the valve section, backlash in a diametrical direction is prevented (prevent out of centering). Also, since caulking is performed only on a side, on which the valve section is mounted, it is unnecessary to perform caulking in the vicinity of the outer periphery of the bracket plate, so that shaft deviation on the bracket plate can be decreased. Thereby, the respective members are good in positional accuracy to maintain coaxiality even in the case of performing caulking.
Preferably, the bracket plate and one end of the valve are put between the projections for caulking and a portion of an end edge of the casing on the other end side, whereby the various solenoid constituents, bracket plate and the valve are assembled.
Thereby, a load of caulking when caulking is performed is imposed only on the plate, one end of the valve, and the casing.
Preferably, a seal ring adapted to come into close contact with the inner peripheral surface of the casing on one end side of the casing to effect sealing is provided, and the casing comprises a small-diameter portion defined by a region, which is disposed on one end side of the casing and includes a portion adapted to be closely contacted by the seal ring, and a large-diameter portion, which is disposed toward the other end from the small-diameter portion of the casing and does not contact with an outer peripheral surface of the seal ring.
Thereby, the large-diameter portion does not contact with the seal ring when the connector member is mounted. Also, that portion (small-diameter portion), with which the seal ring comes into close contact, and for which a comparative accuracy is demanded, can be limited partially. That is, there is no need of enhancing dimensional accuracy or the like for the whole casing member, and so it suffices that the large-diameter portion is rough in accuracy while only the small-diameter portion is high in accuracy.
Preferably, the casing comprises a cylindrical portion, of which an inner peripheral surface defines a substantially perfect circle, and the seal ring is mounted on an inner periphery of the cylindrical portion.
Thereby, airtightness is preferably kept in the casing.
Preferably, the solenoid constituents include an upper plate, of which an end abuts against the inner peripheral surface of the casing and which forms a magnetic path, and an end of the upper plate abuts against an inner peripheral surface of the small-diameter portion of the casing.
Thereby, that portion, against which the upper plate abuts, abuts against that portion (small-diameter portion), which is limited partially, and for which a comparative accuracy is demanded. Thereby, there is no need of enhancing dimensional accuracy or the like for the whole casing member, and so it suffices that the large-diameter portion is rough in accuracy while only the small-diameter portion is high in accuracy.